Most multi-phase motor designs are derived from those originated by Nicola Tesla, and are sometimes described as “squirrel cage” or “rotating field” motors. While these motors are cheap to build, they suffer from low efficiency, armature effect, and excessive heating.
Earlier conversions of squirrel cage motors to permanent magnet merely replaced the rotor iron laminations with permanent magnets. While this configuration had higher efficiency, it then displayed strong “torque cogging” tendencies, and was still subject to the efficiency robbing “armature effect”
Other inventors pursued “fractional slot” configurations of the original “squirrel cage” design, which lowered torque ripple, but at a loss of overall efficiency. Some of their “fractional” stators slots actually rob power and may be considered parasitic “drones”, because they oppose the direction of rotation. This is because all magnetic poles must be considered as balanced in having a north and a south pole, therefore having an even number of poles. Any single pole must, by definition have its opposite pole somewhere else, and in a “fractional” motor this is balanced to an unwanted location.
Patents related to electric motors and generators issued to the inventor of the subject application include U.S. Pat. No. 8,253,299 issued on Aug. 28, 2012; U.S. Pat. No. 8,183,726 issued May 22, 1012; U.S. Pat. No. 7,868,510 issued on Jan. 11, 2011; U.S. Pat. No. 7,798,261 issued on Sep. 21, 2010; U.S. Pat. No. 7,723,891 issued on May 25, 2010; U.S. Pat. No. 7,640,648 issued on Jan. 5, 2010; U.S. Pat. No. 7,579,742 issued on Aug. 25, 2009; U.S. Pat. No. 7,492,074 issued on Feb. 17, 2009 and U.S. Pat. No. 7,343,991 issued on Mar. 18, 2008. These patented technologies use a unique, three stator configuration which frees the design from the efficiency robbing “armature effect”, and achieves much higher overall electrical conversion efficiency. Some “torque ripple”, however, remains.
What is needed to solve the problems associated with prior art “squirrel cage” or “rotating field” motors is a high efficiency low torque ripple multi-phase permanent magnet machine with a new, unique stator configuration that essentially eliminates torque ripple, has improved efficiency, and enhanced smoothness.